Table 2. Parameters controlling spit geometry and evolution, and the associated
processes (from Kraus 1999)
Spit
Long Term1
Parameter
Short Term
Sediment supply; geologic
Longshore transport rate; proximity to
controls; breaching (bayward
inlet channel; strength of channel
or seaward); cyclic &
Length
intermittent forcing
current
Longshore transport rate; grain size;
proximity to inlet channel; beach slope
and depth-contour gradients parallel to
Elongation
Cyclic and intermittent
forcing2
spit
speed
Run-up elevation; tidal range; depth-
Width
contour gradients perpendicular to spit
(see Overwash fans below)
Dunes and other blocking
features; depth of receiving
bay or lagoon
Overwash fans
Elev. above
Aeolian transport; relative
mean sea level
Run up; tidal range
sea-level change; tsunami
Depth of
Wave height and period; tidal range;
closure
grain size
Extreme storms; elapsed time
Tendency to
Proximity to channel; channel current;
recurve
wave focusing; extreme storms
Cyclic and intermittent forcing
1. Long-term processes encompass those of short-term processes in same category.
2. Cyclic and intermittent forcing arises from seasonal and annual changes in wind and
waves, arrival of storms and weather fronts, annual and inter-annual change in water
level, etc.
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